Temporal changes in nutrient concentrations and contents of fine roots in a Quercus forest

Fine-root nutrient concentrations and contents in a Quercus forest, Wisconsin, were measured for 2 years. The nutrients were N, P, S, K, Ca, Mg, Mn, Fe, Zn and Cu. Mean concentration followed the order: N > Ca > K > Fe > Mg > S > P > Mn > Zn > Cu (9.4, 5.9, 4.0, 2.0, 1.8, 1.7, 0.86, 0.82, 0.064, 0.010 g kg^-1 dry weight, respectively). Temporal patterns of P and K concentrations were identical to that of biomass: lower in May than in August and November. N showed an opposite pattern. The concentrations of all other nutrients except Mn showed significant fluctuations but no clear relation to biomass. The contents of N, Fe and Mn changed little over time, whereas the patterns of other nutrients more or less followed biomass. The relationship between nutrient variables and biomass appeared to reflect the geochemical characteristics of individual nutrients.